一般采用整排端口如P1做4X4矩阵，实际上有可能用到两排端口做6X6矩阵键盘，这里做了个6X6键盘-Generally use the whole row of ports, such as P1 to do 4X4 matrix, in fact, may be used to do two rows of 6X6 matrix keyboard port, here made a 6X6 keypad